Chronic inflammatory disease is characterized by chronic, or persistent, inflammation. Chronic inflammatory disease encompasses a large number of diseases, many of which comprise a genetic component. Chronic inflammatory disease can develop as a result of a patient's exposure to harmful stimuli. For example, exposure to certain foods and environmental factors may trigger the development of chronic inflammatory disease. Chronic inflammatory disease can result in pain, fatigue, and digestive problems. Furthermore, the chronic nature of the inflammation may lead to tissue damage which can lead to a variety of additional problems. For example, chronic inflammation in the liver and digestive tract can lead to neurological changes such as fatigue and changes in personality. Chronic inflammation can also alter normal function of organs which can cause systemic disease and disorders in afflicted patients.
Examples of chronic inflammatory disease include celiac disease, vasculitis, lupus, chronic obstructive pulmonary disease (COPD), inflammatory bowel disease, atherosclerosis, arthritis, and psoriasis. Specifically, inflammatory bowel disease is a broad class of chronic inflammatory diseases. Examples of inflammatory bowel diseases are Crohn's disease, ulcerative colitis, collagenous colitis, lymphocytic colitis, ischaemic colitis, diversion colitis, Behcet's disease, indeterminate colitis. While many of these diseases have genetic components, the specific triggers and underlying biochemical causes for the onset of the diseases remain unknown. Furthermore, because the triggers and underlying biochemical causes of the diseases remain largely unknown, treatment regimes merely target reducing the symptoms without eliminating the disease or the chronic inflammation entirely.
Because the inflammation is not easily controlled, constant medication is often administered to lessen the symptoms and side effects of the inflammation. The medications often include antibiotics, aminosalicylates, corticosteroids, immune modifiers, and biologic therapies. However, the medication will often lead to additional pain such as aching joints and headache, fatigue, digestive problems, fever, skin irritation and sensitivity, stomach pain and irritation, dizziness, increased blood pressure, fluid retention, cataracts, glaucoma, high blood sugar, increased risk of infection, osteoporosis, weak bones, suppressed adrenal gland hormone production, and increased risk of bruising and bleeding. Accordingly, even though the inflammation may lessen and worsen throughout the course of the chronic disease with the aid of medical therapies, it is often very difficult to treat and persists with most known treatment regimes.
Inflammatory bowel disease is a debilitating disease that is difficult to treat and incur high treatment cost to patients (Park K T, Bass D. Inflammatory bowel disease-attributable costs and cost-effective strategies in the United States: a review. Inflamm Bowel Dis. 2010; 17(7):1603-9). Inflamed colonic tissues express elevated levels of tumor necrosis factor alpha (TNFα) and other proinflammatory mediators, leading to tissue damage including apoptosis and loss of gut function (Ngo B, Farrell C P, Barr M, Wolov K, Bailey R, Mullin J M, et al. Tumor necrosis factor blockade for treatment of inflammatory bowel disease: efficacy and safety. Curr Mol Pharmacol. 2010; 3(3):145-52). Despite availability of medication like anti-TNFα antibodies, alternative therapeutic solutions are still being actively studied for better efficacy and safety (Rutgeerts P, Vermeire S, Van Assche G. Biological therapies for inflammatory bowel diseases. Gastroenterology. 2009; 136(4):1182-97).
The two major forms of Inflammatory Bowel Disease (IBD) are ulcerative colitis (UC) and Crohn's disease (CD). IBD is a chronic and remitting disease causing inflammation of the intestinal diseases. UC and CD have symptoms and pathologies in common, but they differ in the severity and location of the inflammation along the intestinal tract. Inflammation in UC patients is limited to the mucosal layer, and involves only the rectum and colon, while inflammation in CD patients penetrates the entire wall of the intestine and can occur anywhere along the intestinal tract. A clear diagnosis of the type of IBD is crucial to treatment decisions.
UC typically is characterized by ulcers in the colon and chronic diarrhea mixed with blood, weight loss, blood on rectal examination, and occasionally abdominal pain. UC patients may also present with a variety of other symptoms and extraintestinal manifestations including but not limited to anemia, weight loss, iritis, seronegative arthritis, ankylosing spondylitis, sacroiliitis, erythema nodosum, and pyoderma gangrenosum. Toxic megacolon is a life threatening complication of UC and requires urgent surgical intervention. UC usually requires treatment to go into remission. UC therapy includes anti-inflammatories, immunosuppressants, steroids, and colectomy (partial or total removal of the large bowel, which is considered curative). There is a significantly increased risk of colorectal cancer in UC patients several years after diagnosis, if involvement is beyond the splenic flexure, and a significant risk of primary sclerosing cholangitis, a progressive inflammatory disorder of the bile ducts.
Crohn's disease (CD) is also an IBD feat can affect the colon with symptoms similar to UC. Unlike UC, CD may affect any part of the gastrointestinal tract, and the inflammation penetrates deeper into the layers of the intestinal tact. Patients with CD may have symptoms and intestinal complications including abdominal pain, diarrhea, occult blood, vomiting, weight loss, anemia, fecal incontinence, intestinal obstructions, perianal disease, fistulae, and strictures, and apthous ulcers of the mouth. Extraintestinal complications include skin rashes, arthritis, uveitis, seronegative arthritis, peripheral neuropathy, episcleritis, fatigue, depression, erythema nodosum, pyoderma gangrenosum, growth failure in children, headache, seizures, and lack of concentration. The risk of small intestine malignancy is increased in CD patients. CD is believed to be an autoimmune disease, while it is uncertain whether there is an autoimmune component to UC. There is no known drug or surgical cure for CD; treatment focuses on controlling symptoms and maintaining remission to prevent relapse. Surgery is used for complications of Crohn's (e.g. strictures, fistulae, bleeding), and to remove segments of the intestine with active disease, but there is a high risk of recurrence; thus surgery is not considered curative.
Crohn's disease (CD) is a member of the broad class of inflammatory bowel diseases. One complication of CD is intestinal fibrosis. The intestine of CD patients develops strictures with overexpression of collagen (fibrogenic mediator) due to increased levels of transforming growth factor beta 1 (TGF-b1) and insulin like growth factor-1 (IGF-1), leading to obstruction of intestine and reduced gut motility. Intestines with strictures are unable to move, digest food or absorb nutrients. There is no satisfactory treatment of Crohn's disease associated fibrosis and stricture and surgery is often the only option for these patients. Recurrence of fibrosis or stricture formation is common in CD patients and leads to surgery that can be repeated several times and the disease progresses. Accordingly, intestinal fibrosis or stricture formation is a serious complication of CD and affects the daily live of these patients.
Currently, IBD (such as UC and CD) can only be definitively diagnosed by colonoscopy, a rather invasive procedure; even this invasive procedure is incapable of diagnosing approximately 10% of patients undergoing colonoscopy (Burczynski, J. Mol. Diag. 8 (1): 51 (2006)). Furthermore, there is currently no satisfactory treatment or prevention of intestinal fibrosis and a limited number of effective treatments for the broader class of inflammatory bowel diseases. Thus novel therapeutic modalities to inflammatory bowel diseases, specifically intestinal fibrosis, are needed.
As described herein, cathelicidins are effective at significantly reducing intestinal fibrosis and treat inflammatory bowel diseases. Cathelicidins are a family of endogenous antimicrobial peptides which form a part of the innate immunity that protects the host from infection (Eckmann L. Defence molecules in intestinal innate immunity against bacterial infections. Curr Opin Gastroenterol. 2005; 21(2):147-51). Cathelicidin exists in human as LL-37 and in mice as mCRAMP (Gudmundsson G H, Agerberth B, Odeberg J, Bergman T, Olsson B, Salcedo R. The human gene FALL39 and processing of the cathelin precursor to the antibacterial peptide LL-37 in granulocytes. Eur J Biochem. 1996; 238(2):325-32; Gallo R L, Kim K J, Bernfield M, Kozak C A, Zanetti M, Merluzzi L, et al. Identification of CRAMP, a cathelin-related antimicrobial peptide expressed in the embryonic and adult mouse. J Biol Chem. 1997; 272(20):13088-93). Cathelicidin is secreted from the apical surface that is facing exterior environment such as intestine (Schauber J, Rieger D, Weiler F, Wehkamp J, Eck M, Fellermann K, et al. Heterogeneous expression of human cathelicidin hCAP18/LL-37 in inflammatory bowel diseases. Eur J Gastroenterol Hepatol. 2006; 18(6):615-21) and salivary gland (Murakami M, Ohtake T, Dorschner R A, Gallo R L. Cathelicidin antimicrobial peptides are expressed in salivary glands and saliva. J Dent Res. 2002; 81(12):845-50) by epithelial cells (Schauber J, Rieger D, Weiler F, Wehkamp J, Eck M, Fellermann K, et al. Heterogeneous expression of human cathelicidin hCAP18/LL-37 in inflammatory bowel diseases. Eur J Gastroenterol Hepatol. 2006; 18(6):615-21) and immune cells such as macrophages (Koon H W, Shih D Q, Chen J, Bakirtzi K, Hing T C, Law I, et al. Cathelicidin signaling via the Toll-like receptor protects against colitis in mice. Gastroenterology. 2011; 141(5):1852-63 e1-3).
Cathelicidins possess antimicrobial effects (Ho S, Pothoulakis C, Koon H W. Antimicrobial peptides and colitis. Curr Pharm Des. 2012; 19(1):40-7). Cathelicidin deficient mice have increased chance of infection, have reduced angiogenesis and wound healing (Ramos R, Silva J P, Rodrigues A C, Costa R, Guardao L, Schmitt F, et al. Wound healing activity of the human antimicrobial peptide LL37. Peptides. 2011; 32(7):1469-76). A previous study showed that low plasma level of cathelicidin is associated with increased infectious disease mortality in patients undergoing hemodialysis (Gombart A F, Bhan I, Borregaard N, Tamez H, Camargo C A, Jr., Koeffler H P, et al. Low plasma level of cathelicidin antimicrobial peptide (hCAP18) predicts increased infectious disease mortality in patients undergoing hemodialysis. Clin Infect Dis. 2009; 48(4):418-24. LL-37 mRNA expression is increased in colon biopsies from ulcerative colitis (UC), but not Crohn's disease (CD) patients (Schauber J, Rieger D, Weiler F, Wehkamp J, Eck M, Fellermann K, et al. Heterogeneous expression of human cathelicidin hCAP18/LL-37 in inflammatory bowel diseases. Eur J Gastroenterol Hepatol. 2006; 18(6):615-21). However, it was unknown whether cathelicidin expression in inflammatory bowel disease patients is associated with disease activity. Described herein is the clinical utility of using cathelicidin as a diagnostic biomarker and therapeutic agent.
The effects of intra-colonic and intravenous administration of cathelicidin on an experimental Crohn's disease model is described herein. Specifically, it is shown that intra-colonic and intravenous administration of cathelicidin significantly reduces intestinal fibrosis in an an experimental Crohn's disease model. It is also shown herein that cathelicidin administration also significantly reduced TGF-b1- and IGF-1-induced collagen expression in human colonic fibroblasts.
Furthermore, cathelicidin has been shown by others to possess anti-inflammatory effects in a chemical (dextran sulfate) acute colitis mouse model, a Clostridium difficile infection colitis model, but never in Crohn's disease chronic colitis model associated with fibrosis. As described herein, two in vivo models (chronic trinitrobenzene sulfonic acid (TNBS) with intracolonic cathelicidin peptide and intravenous cathelicidin expressing lentivirus) and one in vitro model (human colonic fibroblasts) were used to demonstrate that cathelicidins have anti-fibrogenic effects. This demonstrates that cathelicidin has direct anti-fibrogenic effects apart from its anti-microbial or anti-inflammatory effects. Thus, exogenous administration of cathelicidin represents a new therapeutic approach against Crohn's disease-associated intestinal fibrosis.
Accordingly, there is a need to develop diagnostic markers and therapeutics for the treatment and diagnosis of Crohn's disease. Described herein are results showing the anti-fibrogenic effects of cathelicidin against Crohn's disease. The results demonstrate that cathelicidin significantly reduces intestinal fibrosis associated with chronic colitis in a relevant animal model. The results also show that cathelicidin reduces TGF-b1 and IGF-1 induced collagen expression in human colonic fibroblasts. Furthermore, the results show that cathelicidin induces ERK phosphorylation in human colonic fibroblasts and that cathelicidin reduces TGF-b1 and IGF-1 induced collagen expression via ERK activation in human colonic fibroblasts. Based on the results described herein, it can be concluded that cathelicidin interferes with cytoskeletal tubulin in human colonic fibroblasts and exerts anti-fibrogenic effects without involving anti-inflammatory or anti-microbial effects.